In an industrial environment, high voltage power is supplied to industrial equipment such as electrical motors. Typically incoming high voltage is supplied to a power distribution unit for distribution to the industrial equipment. At each power cell, each phase of the incoming power is connected to a voltage interrupter, such as a circuit breaker or vacuum interrupter such that when a fault occurs, the interrupter trips to an open state to remove power to the electrical equipment. The power cell typically also includes ground monitoring and ground fault circuits. The output of each power cell is connected directly to the industrial motor via a high voltage coupler.
While the power distribution unit includes indicators to display the status of the incoming high voltage lines, the status of each phase of the voltage is not monitored at the connection to the motor nor is there a physical indication of the status. Instead, when the motor stops, the operator is unable to quickly determine the source of the fault that has caused the motor to stop operating. The fault may be the electrical source, an equipment failure or the motor itself.
For example, the malfunction may be a stuck contactor bottle or stuck mechanical contactor that fails to disconnect when the power is disconnected. The fault leaves the motor circuit energized, undetected by the electrician. If the coupler connecting the high voltage from the power cell to the motor is disconnected from a circuit in an energized state, the disconnection could cause personnel injury or equipment damage.
Another anomaly is when the bottle or contact fails to close, resulting in single phasing and eventually damaging the motor. Also, if a circuit to a hydraulic motor for fan operates in reverse sequence, this fault may result in dangerous or damaging consequences.
To solve the above problems, what is needed is a detection device to provide an indication when the voltage and/or the phase rotation are not correct to protect the operator and prevent equipment damage, thus maximizing production.